A poll released last night by Fox News affords an ideal opportunity to kill two birds with one stone.

Bird No. 1 is the widespread misimpression that more Americans disapprove than approve of President Obama’s performance in his job.

Bird No. 2 is the tendency among most people to ignore or misinterpret the margin of error in public-opinion polls.

The new Fox poll puts the president’s approval rating at 44 percent and his disapproval rating at 49 percent. But that doesn’t necessarily translate into a five-point gap. Actually, the difference is statistically insignificant.

Here’s the deal: The Fox poll has a stated margin of error of plus-or-minus three percentage points with a so-called confidence interval of 95 percent. That means that if Fox conducted the same poll 20 times on the same dates, the results in 19 of those polls would fall within a range of three points lower of three points higher. On one occasion out of 20, the numbers would be pretty much worthless.

It also means that Obama’s approval rating ranges from a low of 41 percent to a high of 47 percent, and his disapproval rating ranges from a low of 46 percent to a high of 52 percent. Since those ranges overlap, the difference is statistically insignificant — although professional pollsters would shy from calling it a tie.

FOOTNOTE: The talking heads on Fox News Channel usually lend an anti-Obama spin to the results of polls commissioned by their company. If there’s a negative available, they’ll find it and trumpet it.

A poll released last night by Fox News affords an ideal opportunity to kill two birds with one stone.

Bird No. 1 is the widespread misimpression that more Americans disapprove than approve of President Obama’s performance in his job.

Bird No. 2 is the tendency among most people to ignore or misinterpret the margin of error in public-opinion polls.

The new Fox poll puts the president’s approval rating at 44 percent and his disapproval rating at 49 percent. But that doesn’t necessarily translate into a five-point gap. Actually, the difference is statistically insignificant.

Here’s the deal: The Fox poll has a stated margin of error of plus-or-minus three percentage points with a so-called confidence interval of 95 percent. That means that if Fox conducted the same poll 20 times on the same dates, the results in 19 of those polls would fall within a range of three points lower of three points higher. On one occasion out of 20, the numbers would be pretty much worthless.

It also means that Obama’s approval rating ranges from a low of 41 percent to a high of 47 percent, and his disapproval rating ranges from a low of 46 percent to a high of 52 percent. Since those ranges overlap, the difference is statistically insignificant — although professional pollsters would shy from calling it a tie.

FOOTNOTE: The talking heads on Fox News Channel usually lend an anti-Obama spin to the results of polls commissioned by their company. If there’s a negative available, they’ll find it and trumpet it.